1. Field of Invention
The present invention relates to liquid dispensers; particularly to wall-mounted dispensers that use liquid container systems having a collapsible bag containing the liquid, an upper fitment, a collapsible, resilient, pump tube and a pump tip with a nozzle through which the liquid is dispensed.
2. Description of Prior Art
The prior art of metered dispensing of single-use portions of fluids from dispensers using a disposable, collapsible bag and a tube to which pressure is applied for flow control, is voluminous. The most significant benefit of this methodology is that all of the components in contact with the fluid path are easily separable from the dispenser, disposable and replaceable, so that the sanitation of such systems is vastly improved over systems with permanent reservoirs and flow components which have to be regularly cleaned.
Liquids and semi-liquids such as food materials, medicines, and cleaning materials are commonly dispensed from countless numbers of existing such dispensers in use around the world. New dispensers are being added to existing markets and new markets constantly.
Wall-mounted liquid soap dispensers which dispense small portions of detergent upon application of pressure to a dispensing lever or member are commonly found in business, industry and institutional restrooms, and constitute a significant specialty industry. The installed base of soap dispensers in the United States alone is estimated at several million.
Rigid containers such as form-fitting blow-molded polyethylene jugs are known to be used with pump tubes in some dispensers, particularly in Europe. A hole is made in the top of the jug, after it is installed in the dispenser, to enable air to replace the liquid as it is consumed.
In another variation, the liquid container is supplied without a pump. The existing pump is removed from the exhausted container and attached to the new container, and reinstalled with the new container.
Many of the existing soap dispensers still use a fixed reservoir which is refilled as required, and needs to be cleaned regularly; but the industry is turning to dispensers that use disposable containers with integral pump tubes, for new and replacement installations. The improvements in ease of service, maintenance and improved sanitation are compelling reasons to use the newer system.
These "bag-in-box" containers hold the liquid soap or other desired material in a collapsible, flexible, transparent bag within a cardboard or paperboard box which is closed for shipping and storage. A pump tube is attached by an upper fitment to the bottom of the bag. The upper fitment may be a two-component rotatable fitment; a flanged upper component that is attached to the bag, and a tube coupling attached to the pump tube. At the lower end of the pump tube is a pump tip with a nozzle from which the liquid is actually expelled.
The box is installed on a shelf in the dispenser, opened for use by tearing out a perforated section in the front and bottom of the box which leaves a slot through which the pump tube is extracted and positioned against a pressure support wall, held by respective upper and lower fitment recesses.
The pump tube is typically made of extruded or molded latex or similar material, and is typically about two and one half inches long, depending on the pump tips and dispensers it is intended to fit.
There is within the pump tip a check valve that resists the free flow of fluid from the bag, but which will yield to the fluid pressure created by a pumping mechanism which squeezes the pump tube in a progressively downward direction to expel the liquid. When the pressure on the tube is removed, the lower end check valve shuts, and the tube expands to its full size, drawing in more fluid and collapsing the bag by a proportionate amount.
The system is sized so that one or two strokes of the pump lever should dispense a sufficient volume of soap for the average user's immediate use.
The check valve may be incorporated into the lower end of the pump tube, rather than actually in the pump tip. Also, some designs include a second check valve on the upper end of the pump tube to prevent back flow of fluid into the bag during the pressure stroke on the pump tube.
In some systems the volume requirement necessitates a larger diameter pump tube than the dispenser's lower recess provides for. Some manufacturers use a molded-in, necked-down tube design to provide the desired working volume and still properly fit the tube recess. This necked-down feature creates a complex pump design that is inevitably more expensive to manufacture than using simple, extruded pump hose that could be cut to length.
The industry has evolved standard dimensions to some areas of the art, such as 500, 800 and 1000 milliliter (ml) disposable soap containers, common lengths for tube/tip combinations and a common size diameter for tube/tip couplings, to which standards both dispensers and disposable soap containers are designed and produced.
The outer shape and finish of soap dispensers vary, but the operating environments are typically warm, wet, and sticky, creating conditions that readily cause the accumulation of dust, scum and grime, making sanitation and maintenance a serious issue. Cracks, slots, ribs, joints and irregular surfaces on dispensers aggravate this problem.
While new dispensers are being installed at significant rate, the market for liquid soap sales is inevitably defined by and directed to the large installed base of existing dispensers. This makes it difficult for manufacturers to introduce new dispensers or containers that depart very much from the interface standards of existing dispenser designs.
However, while container sizes, overall tube/tip length and termination diameters are standardized, internal details of pump tube and pump tip design may vary considerably. This reflects efforts by different manufacturers to improve the technical characteristics and performance of their soap container systems, to get just the right pumping action, the right amount of liquid dispensed, to prevent leaking between dispenses, and to generally improve dispenser performance.
The lower tube/tip locator recess of early dispensers was fundamentally a slot in a lower block sized to accept the lateral insertion of the outer diameter of the lower end of the pump tube.
The problem with this art is that the system depends on the tube's rigidity and the pump mechanism of the dispenser to contain the tube and tip in the recess. This was not always effective. Some pump tips and nozzles are totally unsupported and are susceptible to movement in any direction, caused by movement of the pump tube or deflection by the hand of the user. This can lead to misdirected dispenses, jams, leaks, and premature failure.
Additionally, the wet palm and fingers of the user's hand often contacts the backside, bottom edge of the pump lever when withdrawn, causing an accumulation or build-up of scum at that point. Any protruding or irregular structure on the lower back edge of the lever aggravates this problem.
Keyed elements consisting of various tabs, slots and stepped surfaces have been added to both pump tips and soap dispensers of some manufacturers to inhibit or facilitate, as the case may be, the interchangability of different soap containers and pumps with different dispensers.
Representative background art, U.S. Pat. No. 4,621,749, Kanfer, Nov. 11, 1986, and U.S. Pat. No. 5,265,772, Bartasevich, Nov. 30, 1993, disclose typical dispenser systems that use a "bag-in-box" disposable container. The disclosures and drawings clearly show the reliance on a pump tip and tube combination whereby the outer diameter of the soft wall of the pump tube extends downward into the lower tube recess and provides the majority of contacting surface for lateral restraint of the tube in operation. It is also clear that there is no structure providing specific protection against downward movement of the pump tip through the recess, and no suggestion that such would be useful.
Recent pump tip designs by this inventor, illustrated by FIG. 6D, incorporate an upwardly-extending shank between the keyed elements and the tube coupling nipple, thus displacing the lower end of the tube up out of the recess. This development permitted the use of a shorter pump tube, and offered the potential for a hard interface between the pump tip and the wall of the recess.
The pump tips and tubes of FIGS. 6A, 6B, 6C and 6E illustrate examples of the related art of pump tip designs and designate with dimension L the region that installs into the upper section of a typical lower fitment recess.
In summary, the development of dispensers is in many ways constrained by the configurations of the existing installed base of dispensers. This creates a situation where even small improvements to dispenser and container components which remain compatible with existing designs, while bringing improvements or opportunities for improvements in the maintenance and performance of dispenser/container combinations, are important in the evolution of this art.